About 48 h after birth the lamotrigine concentration of the newborn was in the same range as the umbilical cord blood serum concentration and only about 30% lower than the serum concentration of the mother. This points to a considerable placental transfer, as described also for other AEDs. At term, most anticonvulsants are present in neonatal plasma in concentrations similar to those in maternal plasma. Assuming that the child had just started to suckle some hours before and had correspondingly still not received a relevant amount of lamotrigine via the mother’s milk, this also indicates a relatively long half-life of lamotrigine in the newborn child.